adjective (a)

• not straightforward or candid; giving a false appearance of frankness(adj.all)

  Example:
  An ambitious, disingenuous, philistine, and hypocritical operator, who...exemplified...the most disagreeable traits of his time.
  A disingenuous excuse.
  

  Synonym:
  artful
  Antonym:
  artless, ingenuous
  

  source: wordnet30
• Not noble; unbecoming true honor or dignity; mean; unworthy; as, disingenuous conduct or schemes.(adjective)

  source: webster1913